Adjusts dart2js backend to handle method type arguments.

pkg/compiler/lib/src/resolution/constructors.dart

Index: pkg/compiler/lib/src/resolution/constructors.dart
diff --git a/pkg/compiler/lib/src/resolution/constructors.dart b/pkg/compiler/lib/src/resolution/constructors.dart
index 0f9f09920153103d3f6861c9300d7db6d387368e..7819081db35f1e33f25e007068118da6e2063648 100644
--- a/pkg/compiler/lib/src/resolution/constructors.dart
+++ b/pkg/compiler/lib/src/resolution/constructors.dart
@@ -720,8 +720,25 @@ class ConstructorResolver extends CommonResolverVisitor<ConstructorResult> {
       {PrefixElement prefix}) {
     String name = type.name;
     if (type.isMalformed) {

[Johnni Winther, 2016/05/23 12:50:41]

If you move `if (type.isTypeVariable) ...` before `if (type.isMalformed) ...` no
other changes are needed.

[eernst, 2016/05/23 14:30:24]

Done.

-      return new ConstructorResult.forError(
-          ConstructorResultKind.INVALID_TYPE, type.element, type);
+      if (type is MalformedType) {
+        return new ConstructorResult.forError(
+            ConstructorResultKind.INVALID_TYPE, type.element, type);
+      } else {
+        // GENERIC_METHODS: This block provides thin support for generic
+        // methods: If a method type variable is used as a constructor, a
+        // warning is issued and code for a runtime error generated.
+        assert(type is MethodTypeVariableType);
+        MethodTypeVariableType methodTypeVariableType = type;
+        reporter.reportWarningMessage(
+            node,
+            MessageKind.CANNOT_INSTANTIATE_TYPE_VARIABLE,
+            { 'typeVariableName': methodTypeVariableType.name});
+        registry.registerFeature(Feature.THROW_RUNTIME_ERROR);
+        return new ConstructorResult.forError(
+            ConstructorResultKind.INVALID_TYPE,
+            methodTypeVariableType.toMalformedElement,
+            methodTypeVariableType);
+      }
     } else if (type.isInterfaceType) {
       return new ConstructorResult.forType(prefix, type);
     } else if (type.isTypedef) {